The objective of this research project is to investigate blood flow to the heart in diabetic subjects with and without neuropathy under both resting conditions and after a cold face test, a test that simulates a stress situation like physical or mental work. This test aims to activate nerve fibers to the heart, which control the hearts circulation. In some diabetic subjects, these nerve fibers are damaged and remain present only in small regions of the heart. In diabetes, it is possible that as a result of alterations in the amount of naturally occurring agents which normally control the heart's blood flow, stimulation of these remaining heart nerve fibers may fail to produce the increase in blood flow which is normally observed in people without diabetes. This may lead to impairment of the function of the heart. Diabetic subjects both with and without diabetic neuropathy will be recruited from the Michigan Diabetes Research and Training Center and changes in heart blood flow on sympathetic nerve fiber stimulation will be compared. It is anticipated that blood flow will increase in the subjects with intact nerve fibers, but may paradoxically decrease in subjects with neuropathy. This study should generate important information, which will evaluate the importance of loss of nerve fibers to the heart in diabetes on the hearts circulation. If abnormal responses are found on stimulation of the hearts nerve supply, then this will help the development of treatment strategies in which the aim will be to prevent heart disease complicating diabetes.